The packaging of products containing oil and fat, in particular of dairy products, has to meet a number of different requirements. These requirements, all of which deals with protection to the contents, are briefly described as follows:
(a) Protection Against Light
Foodstuffs sensitive to light, for example products containing fat and oil, suffer from exposure to light during storage and deteriorate in quality, often after a relatively short time. Ultra-violet light rays promote oxidation of the fat and oil components, which is detrimental to taste and olfactory qualities, and results in inedibility. At the same time, other substances such as vitamins and proteins are destroyed.
(b) Protection Against Dehydration
The water vapor permeability of the packaging should be as low as possible. Products containing water, as for example fats, butter, margarine and cream cheese, are adversely affected by loss of water; deterioration results in the edges and surfaces of the packaged product becoming darker and glassy.
(c) Protection Against Oxygen
Exposure to oxygen promotes oxidation reactions and the effects mentioned in paragraph (a) above.
(d) Temperature Resistance
The packaging should be able to withstand as high a filling temperature as possible so that sterile filling can be ensured.
(e) Dimensional Stability
The packaging should be compression-and shock-proof to as high a degree as possible, to protect the product during transport and storage.
All the above requirements are only partly met by packagings generally known heretofore.
The well-known packages, consisting of plastic containers with aluminum tops, are not light-proof at the sharply-formed edges and corners. They do not allow hot filling, and many of the packages show unsatisfactory degrees of water vapor and oxygen impermeability.
All-aluminum packages have the substantial drawback of being extremely susceptible to shock and compression. Therefore, often costly and voluminous bulk packages are needed for transport and storage of products thus packaged.
Recently, packages of laminated foil have been introduced on the market. Packages of this kind combine the advantages of the previously-mentioned methods of packaging, but there are still drawbacks. Mainly, laminated foils allow very little forming. In order to obtain a tray, for example, deep-drawing in several stages is necessary. Even then, the ratio between the surface and depth is not nearly as good as for conventional plastic containers. As a result, deep-drawing, filling and sealing equipment are not efficiently utilized.